Evaluation of the efficacy of the Japanese rabies RC-HL strain vaccine in domestic dogs using past and present data: Prediction based on logistic regression and meta-analysis.

Japan is one of the few rabies-free countries or territories (under the OIE standard) which still implement the policy of mandatory vaccination of domestic dogs. Under the Rabies Prevention Law enacted since 1950, pet owners in Japan are obliged to vaccinate their dogs every year. However, the national vaccination rate is estimated to average 42% over the past decade. Given this low owner compliance, there is debate over whether or not the mandatory vaccination policy should be maintained and if it were to be maintained, whether the yearly booster requirement is necessary or not. Data on 144 companion dogs vaccinated with the Japanese rabies RC-HL strain vaccine were analysed using multiple logistic regression. An extensive literature review was conducted and five previous vaccination studies were selected for meta-analysis. Results of logistic regression indicate that the proportion of dogs having a satisfactory antibody level lasting for 12 months (P_protected) with only one vaccination was 74.7% (95% prediction interval (PI): 51.4%-90.5%). By contrast, P_protected for dogs vaccinated 2-4 times and 5 times or more was estimated as 96.6% (95%PI: 83.1%-99.3%) and 98.7% (95%PI: 96.9%-99.6%), respectively. Moreover, P_protected for 36 months would drop to 33.4% (95%PI: 11.4%-71.6%) for dogs vaccinated only once, while it would be 83.0% (95% PI: 39.4%-97.1%) and 93.0% (95%PI: 59.7%-99.2%) for dogs vaccinated 2-4 times and 5 times or more, respectively. The pooled P_protected for at least 12 months from meta-analysis was estimated as 83.8% (95%CI: 66.1%-97.5%) for dogs vaccinated only once, while it was estimated as 94.7% (95%CI: 87.7%-99.1%) for dogs vaccinated at least twice. Therefore, the yearly booster requirement of the current mandatory vaccination policy in Japan is reasonable in terms of its frequency. However, there is potential for future policy amendment to one that requires less frequent boosters, i.e. a booster is required within one year after primary vaccination and then every two to three years.